The symptoms of Lyme disease are often described in three stages, although not all patients have symptoms of each stage.

SYMPTOMS

First Stage:
The first sign of infection is usually a circular rash called erythema migrans or EM. This rash occurs in about 70-80% of infected persons and begins at the site of the tick bite after a delay of three days to one month. Patients often also experience symptoms such as:
fatigue
chills
fever
headache
muscle and joint pain
swollen lymph nodes

Second Stage:
If the infection goes untreated, the second stage of the disease can last up to several months with possible symptoms including:
central and peripheral nervous system disorders
multiple skin rashes
arthritis and arthritic symptoms
heart palpitations
extreme fatigue and general weakness

Third Stage:
If the infection continues to go untreated, the third stage of the disease can last months to years with possible symptoms including, chronic arthritis and neurological symptoms. If contracted during pregnancy, adverse effects on the fetus, including stillbirth, can occur.

Fatalities from Lyme disease are rare. However, undiagnosed Lyme disease may develop into chronic disease that may be difficult to treat.

DIAGNOSIS

The diagnosis of Lyme disease should be made after evaluation of a patient's symptoms and the risk of exposure to infected ticks. Blood tests may be administered in conjunction with clinical diagnosis to demonstrate the presence of antibodies to the bacteria.

It should be stressed that the results of blood tests cannot be interpreted in the absence of appropriate clinical information (i.e., symptoms of infection). The Public Health Agency of Canada recommends the two-tiered approach for blood testing (i.e., screening blood samples with one test and continued testing only on samples that test positive for Lyme disease) and cautions against the use of invalidated tests or interpretation of results without appropriate guidelines. Blood tests may be negative in patients with early Lyme disease or in patients who have had antibiotic treatment. However, the accuracy of blood tests becomes more reliable as the infection progresses.